c5.hs

fibie :: Integral a => a -> a
fibie a = case a of
  0 -> 0
  1 -> 1
  n -> fibie (n - 1) + fibie (n - 2)

maximum' :: Ord a => [a] -> a
maximum' xs = case xs of
  [] -> error "It's empty"
  [x] -> x
  (x:xs)
    | x > maxVal -> x
    | otherwise -> maxVal
    where maxVal = maximum' xs

replicate' :: (Num a, Ord a) => a -> i -> [i]
replicate' a i 
  | a <= 0    = []
  | otherwise = i:(replicate' (a - 1) i)

take' :: (Num i, Ord i, Eq a) => i -> [a] -> [a]
take' _ [] = []
take' i (first:l)
  | i <= 0        = []
  | first:l == [] = []
  | otherwise     = first : take' (i-1) l

reverse' :: [a] -> [a]
reverse' [] = []
reverse' (x:xs) = reverse' xs ++ [x]

repeat' :: a -> [a]
repeat' a = a : repeat' a

zip' :: [a] -> [b] -> [(a, b)]
zip' [] _ = []
zip' _ [] = []
zip' (x:xs) (y:ys) = (x, y) : zip' xs ys

elem' :: (Eq a) => a -> [a] -> Bool
elem' _ [] = False
elem' a (x:xs) = a == x || elem' a xs

quicksort :: (Ord a) => [a] -> [a]
quicksort [] = []
quicksort (x:xs) = 
  quicksort [xt | xt <- xs, xt <= x] ++ [x] ++ quicksort [xt | xt <- xs, xt > x]